In recent years, smart phones or tablet personal computers (PCs) have been brought to market, and techniques for contact position measurement devices have been actively developed. The smart phones or tablet PCs typically include touch screens, and the user may designate specific coordinates of the touch screen using a stylus pen. The user may input a specific signal to the smart phone through the designation of the specific coordinates of the touch screen.
The current touch screens may identify a position of the stylus pen as well as a type of stylus pen. In response to a plurality of stylus pens being simultaneously contacted, the electronic white board needs to classify the positions and the types of stylus pens.
However, a lot of time is required to detect the positions of the plurality of stylus pens in that the positions of the stylus pens are detected in the time division manner in the related art. For example, in the related art, since a position of a pen A is determined and then a position of a pen B is determined, an amount of time to determine the positions increases as the number of pens is increased, and thus it may be difficult to detect the positions of the plurality of pens in real time.
The touch screens in the related art may detect only positions of stylus pens operated through the same manner. For example, the touch screen capable of detecting a position of a passive type stylus pen may not detect a position of an active type stylus pen. The touch screen capable of detecting a position of the active type stylus pen may not detect a position of the passive type stylus pen. Accordingly, there is a need for a method for simultaneously detecting positions of various types of the stylus pens regardless of the types of the stylus pens.
The current touch screens may detect the position of the stylus pen as well as the writing pressure in the corresponding position, and perform various actions according to the detected position and writing pressure. For this operation, the writing pressure is measured using a variable capacitor of which capacitance is varied according to the writing pressure of the pen in the related art. However, the fine calibration of the variable capacitor s difficult, and thus it is difficult to implement the stylus pens to have the same writing pressure.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.